Breast milk radioactivity following injection of 99Tcm-pertechnetate and 99Tcm-glucoheptonate

Measurements were made of the concentration of radioactivity in the breast milk of two patients: one following 100 MBq (2.7 mCi) 99Tcm-pertechnetate administration, and the other following administration of 550 MBq (15 mCi) 99Tcm-glucoheptonate. The fractional activity concentrations in the former case were about two orders of magnitude greater than in the latter and the effective half lives of secretion were 3 and 4 h, respectively. An infant breast fed without interruption would have ingested 5.2 and 0.055% of the 99Tcm administered with pertechnetate and with glucoheptonate, respectively. The former fractional ingestion was compatible with the larger value expected following pertechnetate injection without perchlorate pretreatment, and would have produced an effective dose equivalent to the infant of 1.5 mSV. An interruption to feeding of 12 h would reduce this dose to 0.2 mSV. It was concluded that breast feeding need not be interrupted after injection of 99Tcm-glucoheptonate other than for a short period of reassurance.